CN109476869B

CN109476869B - Ester-based elastomer foam molded body, use thereof, and ester-based elastomer foam particles

Info

Publication number: CN109476869B
Application number: CN201780043300.XA
Authority: CN
Inventors: 近藤广隆; 权藤裕一
Original assignee: Sekisui Plastics Co Ltd; Toyobo Co Ltd
Current assignee: Dongyang Textile Mc Co ltd; Sekisui Kasei Co Ltd
Priority date: 2016-07-13
Filing date: 2017-05-01
Publication date: 2021-10-15
Anticipated expiration: 2037-05-01
Also published as: WO2018012089A1; JP6253839B1; KR20190029600A; EP3808801A1; US10829607B2; JP2018159049A; TWI637008B; KR102318499B1; US20210040285A1; EP3486278A1; US11834564B2; EP3486278A4; EP3486278B1; TW201802139A; US20190300670A1; CN109476869A

Abstract

An ester elastomer foam molded article is composed of a fused body of foam particles containing an ester elastomer as a base resin.

Description

Ester-based elastomer foam molded body, use thereof, and ester-based elastomer foam particles

Technical Field

The present invention relates to an ester-based elastomer foam molded article, use thereof, and ester-based elastomer foam particles. More specifically, the present invention relates to an ester-based elastomer foam molded body exhibiting high resilience and low density, use thereof, and ester-based elastomer foam particles.

Background

In general, as the cushioning material and the packaging material, an expanded molded article which is a fusion body of a plurality of expanded beads made of polystyrene, polypropylene, or the like is used. The foamed molded article, which is a fusion body of a plurality of foamed particles, can be formed into a complicated shape, and is therefore advantageous compared with a foamed molded article obtained by extrusion foaming. A foamed molded article made of polystyrene, polypropylene or the like has a problem that it is difficult to use the foamed molded article for applications requiring high rebound resilience. Therefore, there is a demand for a foam molded body that can realize high resilience.

In response to the above demand, japanese unexamined patent publication No. 2014-62213 (patent document 1) proposes a foam molded body comprising expanded particles made of thermoplastic polyurethane.

CITATION LIST

Patent document

Patent document 1: japanese unexamined patent publication No. 2014-62213

Disclosure of Invention

Problems to be solved by the invention

While thermoplastic polyurethanes can achieve a certain degree of resiliency, it is difficult to achieve the same resiliency at low densities. Therefore, there is a demand for providing a foam molded body having high resilience even at low density.

Means for solving the problems

The inventors of the present invention have found that by using an ester-based elastomer for a base resin of fused expanded particles forming an expanded molded article, an expanded molded article is provided which has high resilience even at low density, thereby completing the present invention.

The present inventors have also found that ester-based elastomer foamed particles of a foam molded article can be provided, and thus completed the present invention.

Accordingly, the present invention provides an ester-based elastomer foam molded article including a fused body of foam particles containing an ester-based elastomer as a base resin.

The present invention also provides ester-based elastomer foamed particles that contain an ester-based elastomer as a base resin and are capable of providing a foamed molded article including a fused body of the foamed particles.

ADVANTAGEOUS EFFECTS OF INVENTION

The ester-based elastomer foam molded product of the present invention is formed from fused foam particles containing an ester-based elastomer as a base resin, and therefore exhibits high resilience even at low density.

An ester-based elastomer foam molded body exhibiting further high resilience and low density can also be provided in any of the following cases:

(1) the ester-based elastomer comprises a hard segment and a soft segment, the hard segment being formed of a dicarboxylic acid component, and a dicarboxylic acid component and a diol component, and the soft segment being an aliphatic polyether and/or polyester;

(2) the ester-based elastomer has a heat of crystallization of 0 to 30 mJ/mg;

(3) the ester-based elastomer contains a hard segment in a proportion of 30 to 80 mass%;

(4) the dicarboxylic acid component comprises a terephthalic acid component and a dicarboxylic acid component other than the terephthalic acid component and comprises the dicarboxylic acid component other than the terephthalic acid component in a proportion of 5 to 30 mass%;

(5) a dicarboxylic acid component other than the terephthalic acid component is an isophthalic acid component;

(6) the average cell diameter of the center of the expanded particles in the fused body is 10 to 200 [ mu ] m and the average cell diameter of the surface layer is 50 to 300 [ mu ] m;

(7) the polyester elastomer foam molded product has an apparent density of 0.02 to 0.4g/cm³And the rebound resilience is 50-100%; and

(8) the ester elastomer foam molded product is used for any of an insole, a midsole, and an outsole.

The ester-based elastomer foamed particles of the present invention can provide foamed molded articles exhibiting high resilience and low density.

It is also possible to provide expanded particles that can provide an expanded molded body exhibiting further high resilience and low density in any of the following cases:

(a) the ester-based elastomer foamed particles satisfy any of the following requirements (i) to (v):

(i) the ester-based elastomer comprises a hard segment and a soft segment, the hard segment is composed of a dicarboxylic acid component, a dicarboxylic acid component and a diol component, and the soft segment is aliphatic polyether and/or polyester;

(ii) the ester-based elastomer has a heat of crystallization of 0 to 30 mJ/mg;

(iii) the ester-based elastomer contains a hard segment in a proportion of 30 to 80 mass%;

(iv) the ester elastomer foamed particles can provide a foamed molded body in which the average cell diameter of the center portion of the foamed particles in the fused body is 10 to 200 [ mu ] m and the average cell diameter of the surface layer portion is 50 to 300 [ mu ] m; and

(v) the ester-based elastomer foam particles can provide an apparent density of 0.02 to 0.4g/cm³A foam molded body having a resilience of 50 to 100%;

(b) the dicarboxylic acid component comprises a terephthalic acid component and a dicarboxylic acid component other than the terephthalic acid component and comprises the dicarboxylic acid component other than the terephthalic acid component in a proportion of 5 to 30 mass%; and

(c) the dicarboxylic acid component other than the terephthalic acid component is an isophthalic acid component.

Drawings

FIG. 1 is a sectional view of the foam molded body of example 1.

FIG. 2 is a sectional view of the foam molded article of example 2.

FIG. 3 is a sectional view of the foam molded article of example 3.

FIG. 4 is a sectional view of the foam molded article of example 4.

FIG. 5 is a sectional view of the foam molded body of example 5.

FIG. 6 is a sectional view of the foam molded body of example 6.

FIG. 7 is a sectional view of the foam molded article of example 7.

FIG. 8 is a sectional view of the foam molded body of example 8.

FIG. 9 is a sectional view of the foam molded body of example 9.

FIG. 10 is a sectional view of the foam molded article of example 10.

FIG. 11 is a sectional view of the foam molded article of example 11.

FIG. 12 is a sectional view of the foam molded body of comparative example 1.

FIG. 13 is a sectional view of the foam molded body of comparative example 2.

[ FIG. 14 ]]For the ester-based elastomer of example 1¹H-NMR spectrum.

[ FIG. 15 ]]For the ester-based elastomer of example 2¹H-NMR spectrum.

[ FIG. 16 ] A]For the ester-based elastomer of example 3¹H-NMR spectrum.

[ FIG. 17 ]]For the ester-based elastomer of example 4¹H-NMR spectrum.

[ FIG. 18 ]]For the ester-based elastomer of example 5¹H-NMR spectrum.

[ FIG. 19 ]]For the ester-based elastomer of example 6¹H-NMR spectrum.

Detailed Description

The ester-based elastomer foam molded article of the present invention (hereinafter simply referred to as foam molded article) includes a fusion body of foamed particles containing an ester-based elastomer as a base resin.

(1) Ester-based elastomer

The ester-based elastomer is not particularly limited as long as the ester-based elastomer provides a foam molded article exhibiting high resilience and low density. Examples thereof include ester-based elastomers containing hard segments and soft segments.

The hard segment may be formed from, for example, a dicarboxylic acid component and/or a diol component. The hard segment may be formed from two components: a dicarboxylic acid component, and a dicarboxylic acid component and a diol component.

Examples of dicarboxylic acid components include components derived from: such as aliphatic dicarboxylic acids and derivatives thereof, e.g., oxalic acid, malonic acid, and succinic acid, and aromatic dicarboxylic acids and derivatives thereof, e.g., terephthalic acid, isophthalic acid, and naphthalene dicarboxylic acid.

Examples of the diol component include: c_2-10Alkylene glycols, such as ethylene glycol, propylene glycol, and butylene glycol (e.g., 1, 4-butylene glycol); (poly) oxy C_2-10An alkylene glycol; c_5-12A cycloalkane diol; bisphenols and alkylene oxide adducts thereof. The hard segment may have crystallinity.

The soft segments used may be polyester and/or polyether segments.

Examples of polyester type soft segments include: aliphatic polyesters, e.g. dicarboxylic acids (e.g. aliphatic C of adipic acid)_4-12Dicarboxylic acids) and glycols (e.g. C, 1, 4-butanediol_2-10Alkylene glycols and (poly) oxy C's, e.g. ethylene glycol_2-10Alkylene glycol), polycondensates of hydroxycarboxylic acids (oxycarboxylic acids), and lactones (e.g., C such as. epsilon. -caprolactone)_3-12Lactones) are used. The polyester soft segment can be amorphous. Specific examples of the polyester as the soft segment include caprolactone polymers, and C_2-6Alkylene glycol with C_6-12Polyesters of alkanedicarboxylic acids such as polyethylene adipate and polybutylene adipate, and the like. The number average molecular weight of the polyester may be in the range of 200 to 15000, in the range of 200 to 10000, or in the range of 300 to 8000. The number average molecular weight may be 200, 300, 500, 1000, 3000, 5000, 8000, 10000, 12000 or 15000.

Examples of the polyether type soft segment include segments derived from aliphatic polyethers such as polyalkylene glycols (e.g., polyoxyethylene glycol, polyoxypropylene glycol, and polyoxytetramethylene glycol). The polyether may have a number average molecular weight of 200 to 10000, 200 to 6000, or 300 to 5000. The number average molecular weight may be 200, 300, 500, 1000, 2000, 4000, 5000, 6000, 8000 or 10000.

The soft segment may be a segment derived from: polyesters having polyether units such as copolymers of aliphatic polyesters and polyethers (polyether-polyesters), and polyesters of polyethers such as polyoxyalkylene glycols (e.g., polyoxytetramethylene glycol) and aliphatic dicarboxylic acids.

The mass ratio of the hard segment to the soft segment may be 20:80 to 90:10, 30:70 to 80:20, 40:60 to 80:20, or 40:60 to 75: 25. The mass ratio may be 20:80, 25:75, 30:70, 40:60, 50:50, 60:40, 70:30, 75:25, 80:20, or 90: 10.

When the dicarboxylic acid component comprises a terephthalic acid component and a dicarboxylic acid component other than the terephthalic acid component, the ester-based elastomer may comprise 30 to 80 mass% of the hard segment and 5 to 30 mass% of the dicarboxylic acid component other than the terephthalic acid component. The content ratio of the hard segment may be 30 mass%, 35 mass%, 40 mass%, 45 mass%, 50 mass%, 55 mass%, 60 mass%, 65 mass%, 70 mass%, 75 mass%, or 80 mass%. The proportion of the dicarboxylic acid component other than the terephthalic acid component may be 5 to 25 mass%, 5 to 20 mass%, or 10 to 20 mass%. The ratio may be 5 mass%, 7 mass%, 10 mass%, 12 mass%, 15 mass%, 17 mass%, 20 mass%, 22 mass%, or 25 mass%. The proportion of the dicarboxylic acid component can be obtained by quantitatively evaluating the NMR spectrum of the resin.

The dicarboxylic acid component other than the terephthalic acid component is preferably an isophthalic acid component. The inclusion of the isophthalic acid component tends to lower the crystallinity of the elastomer and can improve the foam moldability, thereby providing a foam molded body having a lower density.

Ester-based elastomers suitably used may be PELPRENE series and VYLON series elastomers manufactured by Toyobo co. The use of PELPRENE series elastomers is particularly preferred.

(2) Base resin

The melting point of the base resin may be 100 to 200 ℃. When the melting point exceeds 200 ℃, it is difficult to soften during foaming and a foamed molded body of low density is not obtained. When the melting point is less than 100 ℃, shrinkage may occur after the pre-foaming step and forming may be difficult. The melting point of the resin can be 120-200 ℃ or 120-190 ℃. The melting point may be 100 deg.C, 120 deg.C, 130 deg.C, 140 deg.C, 150 deg.C, 160 deg.C, 170 deg.C, 180 deg.C, 190 deg.C or 200 deg.C.

The crystallization heat of the base resin may be 0 to 30 mJ/mg. When the heat of crystallization exceeds 30mJ/mg, the foam moldability may decrease and it may be difficult to obtain a foam molded body of low density. The crystallization heat may be 3 to 30mJ/mg, 6 to 30mJ/mg, or 9 to 30 mJ/mg. The heat of crystallization can be 0mJ/mg, 3mJ/mg, 6mJ/mg, 9mJ/mg, 10mJ/mg, 15mJ/mg, 20mJ/mg, 25mJ/mg, or 30 mJ/mg.

The base resin may have a D hardness of 65 or less. When the D hardness exceeds 65, softening during foaming may be difficult and a low-density foamed molded body may not be obtained. The D hardness may be 20 to 60, 25 to 60, or 30 to 60. The D hardness may be 0, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60.

The base resin may contain a resin other than the ester-based elastomer within a range not to deteriorate the effect of the present invention. The resin other than the ester-based elastomer may be a known thermoplastic resin or thermosetting resin.

The base resin may further contain a flame retardant, a colorant, an antistatic agent, a spreading agent, a plasticizer, a flame retardant aid, a crosslinking agent, a filler, a lubricant, or the like.

Examples of flame retardants include hexabromocyclododecane, triallylisocyanurate hexabromide, and the like.

Examples of the colorant include: inorganic pigments such as carbon black, graphite, and titanium oxide; organic pigments such as phthalocyanine blue, quinacridone red and isoindolinone yellow; a metal powder; special pigments, such as pearl (pearl); and dyes and the like.

Examples of the antistatic agent include polyoxyethylene alkylphenol ethers, stearic acid monoglyceride, and the like.

Examples of the spreading agent include polybutene, polyethylene glycol, silicone oil, and the like.

(3) Expanded particles in fusion body

The foam molded article includes a fused body formed by fusing a plurality of foamed particles containing an ester-based elastomer as a base resin.

The fusion body as used herein refers to a fusion body of expanded particles having a fusion rate of 1% or more, in which 25% or more of the line of the interface of the expanded particles having the largest cross-sectional area is connected to other expanded particles when a sectional image of the expanded molded body is taken under an electron microscope. The proportion of the line connected to the other expanded particles may be 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%. The fusion rate may be 1%, 20%, 40%, 60%, 80%, or 100%.

The average particle diameter of the expanded beads in the fused body may be 1 to 15 mm. The average particle diameter means an average value of values obtained by measuring the maximum value and the minimum value of the diameters of 20 foamed particles at the cross section of the fusion body and by the calculation of (maximum value + minimum value)/2. The average particle size may be 1mm, 3mm, 5mm, 7mm, 10mm, 12mm or 15 mm.

The average cell diameter of the foamed particles in the fused body may be 10 to 200 μm in the center portion and 50 to 300 μm in the surface layer portion. When the average cell diameter is less than 10 μm, the foamed molded article shrinks. When the average cell diameter is more than 300 μm, fusion between the expanded particles may be deteriorated and strength may be reduced. The average bubble diameter of the central portion may be 10 μm, 30 μm, 50 μm, 70 μm, 100 μm, 130 μm, 150 μm, 170 μm, or 200 μm. The average cell diameter of the surface layer portion may be 50 μm, 70 μm, 100 μm, 130 μm, 150 μm, 170 μm, 200 μm, 250 μm, or 300 μm. The average bubble diameter at the center portion may be smaller than the average bubble diameter at the surface layer portion.

The central portion and the surface layer portion as used herein mean the following regions a and B, respectively. That is, an image of a cross section of the foamed molded body was taken under a 15-fold magnification. An image was printed on a4 paper, and foamed particles having as large a cross-sectional area as possible were selected from the printed image. On the selected expanded particles, the minimum diameter and the maximum diameter through the center are plotted. From the center, a circle with a radius of 2/5 based on the smallest diameter is drawn. The inner side of the drawn circle is regarded as an area a as the center portion. In addition, from the center, a circle having a radius of 13/15 based on the maximum diameter is drawn. The outside of the drawn circle is regarded as a region B as a surface layer portion. The average bubble diameter means a value as measured according to the method described in the examples.

(4) Foamed molded article

The density of the foamed molded article may be 0.02 to 0.4g/cm³. When the density is more than 0.4g/cm³Lightness of the foam molded articleIt will decrease. When the density is less than 0.02g/cm³In the case, the foamed molded article may shrink to have a poor appearance or may have a reduced strength. The density can be 0.04-0.4 g/cm³In the range of 0.06 to 0.4g/cm³In the range of 0.06 to 0.3g/cm³Within the range of (1). The density may be 0.02g/cm³、0.04g/cm³、0.06g/cm³、0.1g/cm³、0.2g/cm³、0.3g/cm³Or 0.4g/cm³。

The foam molded article may have a rebound resilience of 50 to 100%. When the resilience is less than 50%, it may be difficult to use the foam-molded article for applications requiring resilience. The resilience may be 50%, 60%, 70%, 80%, 90% or 100%.

The closed cell ratio (closed cell ratio) of the foam molded article may be 60 to 100%. When the closed cell ratio is less than 60%, it may be difficult to apply internal pressure and the formability may be deteriorated. The closed cell porosity may be in the range of 65 to 100%, or in the range of 70 to 100%. The closed cell fraction may be 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100%.

The compression set of the foam molded article may be 0 to 15%. When the compression set is more than 15%, it may be difficult to use the foam-molded article in an environment having a compressive stress. The compression set may be in the range of 0 to 13%, or in the range of 0 to 11%. The compression set may be 0%, 2%, 4%, 6%, 8%, 11%, 13% or 15%.

The foamed molded body may have a 25% compressive stress of 30kPa or more and a 50% compressive stress of 100kPa or more. When the 25% compressive stress is less than 30kPa and the 50% compressive stress is less than 100kPa, it may be difficult to use the foamed molded body in an environment having a compressive stress. The 25% compressive stress may be in the range of 30 to 300kPa, and the 50% compressive stress may be in the range of 50 to 500 kPa. The 25% compressive stress may be 30kPa, 100kPa, 300kPa, 700kPa, or 1000 kPa. The 50% compressive stress may be 30kPa, 100kPa, 500kPa, 700kPa, or 1000 kPa.

The C hardness of the foam molded article may be 20 or more. When the C hardness is less than 20, the foamed molded body may have reduced shape stability. The C hardness may be in the range of 20 to 65, in the range of 20 to 60, or in the range of 20 to 55. The C hardness may be 20, 30, 40, 50, 55, 60, or 65.

The fusion ratio of the foam molded article may be 5 to 100%. When the fusion ratio is less than 5%, the foamed molded article may not have sufficient strength. When the fusion ratio is 5 to 100%, the foamed molded article has sufficient strength. The fusion rate may be 10 to 100%, 15 to 100%, or 20 to 100%. The fusion rate may be 5%, 10%, 15%, 20%, 25%, 30%, 50%, 70%, or 100%.

The foamed molded article can be used, for example, for: a midsole, an insole and an outsole forming a sole of the shoe; core materials for hitting tools of sports goods such as rackets and bats; protective tools for sporting goods such as mats and protectors; medical, care, welfare and health care products such as pads and braces; tire core materials for bicycles, wheelchairs and the like; interior materials for conveying machines such as automobiles, seat core materials, impact absorbing members, and vibration absorbing members; cushioning materials such as fender materials (fenders) and floating bodies (floats); a toy; floor base material (floor base material); a wall material; a railway vehicle; an aircraft; a bed; and a cushion (cushion).

The foamed molded article of the present invention may be used for any or all of a midsole, an insole and an outsole. Any of the midsole, insole and outsole not comprising the foamed molded body of the present invention may be a known midsole, insole or outsole.

The foam molded product may have an appropriate shape according to the application.

(5) Method for producing foam molded body

The foamed molded article can be obtained by molding foamed particles in a mold, and includes a fused body of a plurality of foamed particles. For example, a closed metal mold having many small pores may be filled with expanded particles (pre-expanded particles), and the expanded particles may be heat-expanded with pressurized steam to fill the voids between the expanded particles and fuse and integrate the expanded particles into one body, thereby obtaining an expanded molded body. The density of the foamed molded body can be adjusted, for example, by adjusting the filling amount of the foamed particles in the metal mold.

Further, in order to increase the foaming force of the foamed particles (internal pressure applying step), the foamed particles may be impregnated with an inert gas or air (hereinafter referred to as an inert gas or the like). By increasing the foaming force, the fusibility of the foamed particles during in-mold forming is improved, thereby providing a foamed molded body having further improved mechanical strength. Examples of the inert gas include carbon dioxide, nitrogen, helium, argon, and the like.

Examples of the method for impregnating the foamed particles with the inert gas or the like include a method in which the foamed particles are placed under an atmosphere of the inert gas or the like at atmospheric pressure or higher to impregnate the foamed particles with the inert gas or the like. The expanded particles may be impregnated with an inert gas or the like before filling the metal mold, or the expanded particles may be impregnated by placing the metal mold containing the expanded particles in an atmosphere of an inert gas or the like. When the inert gas is nitrogen, the expanded beads may be left in a nitrogen atmosphere of 0.1 to 2MPa gauge pressure (based on atmospheric pressure) for 20 minutes to 24 hours.

When the expanded particles are impregnated with an inert gas or the like, the expanded particles may be heated and expanded in a metal mold. However, the expanded particles may be heated and expanded before filling the metal mold to obtain expanded particles having a low bulk density, and then the metal mold may be filled and heating and expansion may be performed. By using expanded particles having a low bulk density, a low-density expanded molded body can be obtained.

When the coalescence inhibitor described below is used during production of the expanded particles, the expanded particles containing the coalescence inhibitor attached to the expanded particles may be shaped during production of the expanded molded body. To promote the fusion of the expanded particles, the coalescence inhibitor may be washed and removed prior to the forming step, or a fusion promoter such as stearic acid may be added during the forming with or without removing the coalescence inhibitor.

(a) Process for producing expanded beads

The expanded particles of the present invention are expanded particles that contain an ester-based elastomer as a base resin and can provide an expanded molded article including a fused body of the expanded particles.

The expanded particles preferably satisfy any of the following requirements (i) to (v):

(i) the ester-based elastomer comprises a hard segment and a soft segment, the hard segment being formed of a dicarboxylic acid component, and a dicarboxylic acid component and a diol component, and the soft segment being an aliphatic polyether and/or polyester;

(ii) the ester-based elastomer has a heat of crystallization of 0 to 30 mJ/mg;

(iv) the expanded particles can provide an expanded molded body in which the average cell diameter of the central portion of the expanded particles in the fused body is 10 to 200 μm and the average cell diameter of the surface layer portion is 50 to 300 μm; and

(v) the foamed particles can provide a display density of 0.02 to 0.4g/cm³And a resilience of 50 to 100%.

It is also preferable that the dicarboxylic acid component contains a terephthalic acid component and a dicarboxylic acid component other than the terephthalic acid component and contains the dicarboxylic acid component other than the terephthalic acid component in a proportion of 5 to 30 mass%.

Further, the dicarboxylic acid component other than the terephthalic acid component is preferably an isophthalic acid component.

The requirements and details for the dicarboxylic acid component are the same as the corresponding details for the foamed shaped body.

The expanded particles can be obtained by a step of expanding the expandable particles (foaming step).

The volume density of the foaming particles can be 0.015-0.4 g/cm³Within the range of (1). When the volume density is less than 0.015g/cm³In the case of the foam molded article, the obtained foam molded article may shrink to cause a poor appearance, and the foam molded article may have a reduced mechanical strength. When the bulk density is more than 0.4g/cm³In the case, the lightweight property of the foam molded article is lowered. The bulk density can be 0.03-0.4 g/cm³Or 0.05 to 0.4g/cm³。

The expanded particles may have any shape without limitation, and examples of the shape include spherical, ellipsoidal (egg-shaped), cylindrical, prismatic, pellet-shaped, and granular shapes and the like.

The average particle diameter of the expanded beads may be 1 to 15 mm. When the average particle diameter is less than 1mm, production of foamed particles may be difficult per se and production costs may increase. When the average particle diameter is more than 15mm, the filling property in the metal mold may be lowered during the production of a foam-molded body by molding in the mold. The average particle diameter of the expanded particles (excluding the average particle diameter of the expanded particles in the fused body) means an average value of values obtained by measuring the maximum value and the minimum value of the diameters of 20 expanded particles and by the calculation of (maximum value + minimum value)/2.

In the foaming step, the foaming temperature and the heating medium are not particularly limited as long as the expandable particles can be foamed to obtain expanded particles.

The expanded particles may be prepared by the following process: a method including supplying resin particles, water, a dispersant, a foaming agent, and the like to an autoclave, heating it to impregnate the resin particles with the foaming agent, and then releasing from the autoclave into a low pressure to obtain foamed particles (release foaming); or a method including supplying a base resin and a foaming agent and the like to an extruder, melt-kneading them, and extruding at a lower pressure than in the extruder to foam and cut to obtain foamed particles (extrusion foaming).

In the foaming step, a coalescence inhibitor may be added to the expandable particles. The amount of the coalescence inhibitor to be added may be in the range of 0.03 to 0.3 parts by mass or in the range of 0.05 to 0.25 parts by mass per 100 parts by mass of the expandable beads. When the coalescence inhibitor is less than 0.03 parts by mass, a sufficient coalescence-inhibiting effect cannot be obtained. When the coalescence inhibitor is more than 0.3 parts by mass, the foamed molded body may have reduced strength or the washing cost may increase.

Before foaming, the surface of the expandable particles may be coated with a powdered metal soap such as zinc stearate, calcium carbonate or aluminum hydroxide. The coating reduces the adhesion between the expandable particles during the expansion step. Alternatively, a surface treatment agent such as an antistatic agent or a spreading agent may be applied.

(b) Process for producing expandable beads

The expandable particles can be obtained by a step of impregnating resin particles with a foaming agent to thereby obtain expandable particles (impregnation step).

The blowing agent may be an organic gas or an inorganic gas. Examples of the inorganic gas include air, nitrogen, and carbon dioxide (carbonic acid gas). Examples of organic gases include hydrocarbons such as propane, butane and pentane, and fluorine-containing blowing agents. The blowing agent used may be only one kind or a combination of two or more kinds.

The amount of the foaming agent in the base resin may be 1 to 12 parts by mass per 100 parts by mass of the base resin. When the amount is less than 1 part by mass, foaming power may be reduced and good foaming may not be obtained. When the content of the foaming agent is more than 12 parts by mass, the bubble film may be damaged, the plasticizing effect may be excessive, the viscosity may be reduced during foaming, and shrinkage may occur. The amount of the physical blowing agent may be 5 to 12 parts by mass. The amount within the range allows sufficient increase in foaming force and further good foaming.

The method for impregnating the resin particles with the physical blowing agent may be any known method. Examples thereof include a wet impregnation method and a dry impregnation method. The wet impregnation method is a method in which resin particles, a dispersant and water are supplied in an autoclave, stirred to disperse the resin particles in the water and produce a dispersion, and a foaming agent is injected into the dispersion to impregnate the resin particles with the foaming agent. The dry impregnation method is a method in which a foaming agent is injected into resin particles in an autoclave to impregnate the resin particles with the foaming agent.

The dispersing agent is not particularly limited and examples thereof include: sparingly water-soluble inorganic substances such as calcium phosphate, magnesium pyrophosphate, sodium pyrophosphate and magnesium oxide, and surfactants such as sodium dodecylbenzenesulfonate.

When the temperature for impregnating the resin particles with the physical blowing agent is low, the time required for impregnating the resin particles with the physical blowing agent is prolonged, causing a decrease in production efficiency. When the temperature is high, the resin particles may fuse with each other to produce bonded particles. The dipping temperature can be-20 to 120 ℃, 0 to 120 ℃,20 to 120 ℃ or 40 to 120 ℃. The physical blowing agent may be used in combination with a blowing aid (plasticizer) or a bubble adjusting agent.

Examples of the blowing aid (plasticizer) include diisobutyl adipate, toluene, cyclohexane, ethylbenzene and the like.

Examples of the bubble adjusting agent include higher fatty acid amides, higher fatty acid bisamides, higher fatty acid salts, inorganic bubble nucleating agents, and the like. The bubble control agent may be a combination of more than one.

Examples of the higher fatty acid amide include stearic acid amide, 12-hydroxystearic acid amide and the like.

Examples of the higher fatty acid bisamide include ethylene bis (stearic acid amide), methylene bis (stearic acid amide), and the like.

Examples of the higher fatty acid salt include calcium stearate and the like.

Examples of inorganic bubble nucleating agents include talc, calcium silicate, and synthetic or naturally occurring silica, among others.

In addition to the above, a bubble adjusting agent that can be used as a chemical blowing agent may be used. Examples of such bubble modifiers include sodium bicarbonate-citric acid, sodium bicarbonate, azodicarbonamide, dinitrosopentamethylenetetramine, benzenesulfonylhydrazide, hydrazonodicarbonamide, and the like.

The content of the bubble control agent may be 0.005 to 2 parts by mass or 0.01 to 1.5 parts by mass per 100 parts by mass of the expandable beads. When the bubble adjusting agent is less than 0.005 parts by mass, the control of the bubble diameter may be difficult. When the bubble adjusting agent is more than 2 parts by mass, the resin physical properties may be changed and, for example, the molded article may have reduced strength.

(c) Resin particle

The shape of the resin particles is not particularly limited, and examples thereof include spherical, ellipsoidal (egg-shaped), cylindrical, prismatic, pellet-shaped, and granular shapes and the like.

The resin particles may be raw material pellets without further processing or may be those obtained by re-granulation to an arbitrary size and shape.

The resin particles may have a length of 0.5 to 5mm and an average diameter of 0.5 to 5 mm. When the length is less than 0.5mm and the average diameter is less than 0.5mm, the expandable beads thus obtained may have low gas retentivity, and thus expansion may be difficult. When the length is more than 5mm and the average diameter is more than 5mm, heat cannot reach the inside during foaming and thus the fused foamed particles may have a core. The length L and the average diameter D of the resin particles were measured using calipers as follows: the length of the resin particle in the extrusion direction at the time of re-pelletization was regarded as length L, and the average of the minimum diameter and the maximum diameter of the resin particle in the direction perpendicular to the extrusion direction was regarded as average diameter D. When the raw material pellets are used without further processing, the longest diameter of the resin particles is taken as the length L and the average of the smallest diameter and the largest diameter in a direction perpendicular to the direction of the longest diameter is taken as the average diameter D.

Examples

The present invention is described more specifically below by way of examples which do not limit the invention.

< melting Point, crystallization temperature and Heat of crystallization of resin pellets >

The measurement was carried out in accordance with JIS K7121:1987,2012 "method for measuring transition temperature of Plastic" and JIS K7122:1987,2012 "method for measuring transition temperature of Plastic". The sampling and temperature conditions were as follows. The bottom of the aluminum measurement container was filled with about 6mg of the sample without a gap, and on a differential scanning calorimeter (DSC6220ASD-2, manufactured by SII nanotechnology, inc., or DSC7000X AS-3, manufactured by Hitachi High-Tech Science Corporation), the sample was cooled down from 30 ℃ to-70 ℃ at a nitrogen flow of 20mL/min, held for 10 minutes, warmed up from-70 ℃ to 220 ℃ (first warming), held for 10 minutes, cooled down from 220 ℃ to-70 ℃ (cooled down), held for 10 minutes, and then warmed up from-70 ℃ to 220 ℃ (second warming), thereby obtaining a DSC curve. When no melting peak is observed in the range of-70 to 220 ℃, the upper limit temperature of the first temperature rise and the second temperature rise is set with the melting point Tm +40 ℃ as a guide. For example, polyethylene terephthalate is warmed from-70 ℃ to 290 ℃. All temperature increases and decreases were performed at a rate of 10 ℃/min and the reference material used was alumina. The melting point as in the present invention is the temperature at the top of the highest melting peak observed during the second ramping procedure, read with analytical software connected to a calorimeter. The crystallization temperature is the temperature at the top of the crystallization peak on the highest temperature side observed during the cooling down process, read with analytical software connected to a calorimeter. The heat of crystallization was calculated from the area enclosed by the DSC curve and a straight line connecting the point at which the DSC curve departs from the baseline on the high temperature side and the point at which the DSC curve returns to the baseline on the low temperature side, by using analysis software connected to a calorimeter.

< D hardness of resin pellets >

The resin particles were hot-pressed at a temperature of melting point Tm +20 ℃ to prepare a smooth film having a thickness of 3mm or more. The film was conditioned for 72 hours or more in an environment having a temperature of 23 ± 2 ℃ and a humidity of 50 ± 5%, and then measured with a Durometer (Teclock Durometer type D, manufactured by Teclock Corporation). The pressing surface was brought into close contact with the test piece so that the stylus was perpendicular to the measurement surface of the test piece, and the scale was immediately read. The samples were measured at 5 points and the average value was obtained as D hardness.

< bulk Density of expanded particles >

An arbitrary mass w (g) of the foamed particles was weighed as a measurement sample. The nominal volume V (cm) of the sample was determined by allowing the measurement sample to fall naturally in the measuring cylinder and tapping the bottom of the measuring cylinder to make the volume constant³). The bulk density of the expanded particles is calculated according to the following equation:

bulk Density (g/cm)³) Mass of measurement sample W/volume of measurement sample V

< Density of foam molded article >

The foam molded body was dried at 40 ℃ for 12 hours immediately after molding and was conditioned at 23. + -. 2 ℃ and 50. + -. 5% humidity for 72 hours after drying. Weighing the state-adjusted foam molded body to two decimal places andthe external dimensions were measured to 1/100mm with an electronic digital caliper (manufactured by Mitutoyo Corporation) to determine a nominal volume b (cm)³). The density of the foamed molded body is calculated according to the following equation:

density (g/cm) of foam molded article³)＝a/b

< average cell diameter (surface layer portion) and average cell diameter (center portion) of foam molded body >

The average cell diameter of the foamed molded body was measured according to the following method. Specifically, 3 test pieces (thickness: 1mm) were cut out from the foamed molded body with a spatula and an image of the cross section was taken under 15-fold magnification on a scanning electron microscope (S-3000N, manufactured by Hitachi, Ltd., or S-3400N, manufactured by Hitachi High-Technologies Corporation). Images were printed on a4 paper and foamed particles having as large a cross-sectional area as possible were selected from each printed image. On the selected expanded particles, the minimum diameter and the maximum diameter through the center are plotted. From the center, a circle with a radius of 2/5 based on the smallest diameter is drawn. The inner side of the drawn circle is regarded as an area a as the center portion. In addition, from the center, a circle having a radius of 13/15 based on the maximum diameter is drawn. The outside of the drawn circle is regarded as a region B as a surface layer portion.

An arbitrary straight line is drawn so that the straight line contacts 20 or more bubbles in the area a, the length L of the straight line is measured and the number N of bubbles contacting the straight line is counted. When the straight line contacting 20 bubbles cannot be drawn, the longest straight line within the area is drawn. The arbitrary straight line is carefully drawn so that the straight line does not contact the bubble only at the point where the bubble contacts the adjacent bubble. However, when the straight line comes into contact with the bubble at the above-mentioned point, the adjacent bubbles are also counted. When the bubbles are too small to count, an image magnified 15 times more may be used, and when the foamed particles are too large to accommodate a 15 times magnified image, an image magnified 15 times less may be used. From the measurement results, the average chord length t and the bubble diameter D are calculated according to the following equations.

Average chord length t is line length L/(bubble number N x image magnification)

Bubble diameter D-average chord length t/0.616

The same measurement was performed for each test piece and the arithmetic average thereof was regarded as the average bubble diameter (center portion).

The same calculation is performed for the region B, and the arithmetic average thereof is taken as the average bubble diameter (surface layer portion).

< closed cell fraction of foamed molded article >

The foam molded body was cut to 25X thickness 20mm while leaving the outer layer on two planes perpendicular to the thickness direction, and the condition adjustment was performed for 16 hours under the environment of JIS K7100:1999, symbol 23/50, grade 2, followed by measurement under the environment of JIS K7100:1999, symbol 23/50, grade 2. The mass (g) of the obtained test piece was weighed to two decimal places, and the outer dimension was measured to 1/100mm with an electronic digital caliper (manufactured by Mitutoyo Corporation), thereby determining a nominal volume A (cm)³). Next, the volume B (cm) of the measurement sample was determined by an air comparison type densitometer (model 1000, manufactured by Tokyouscience Co., Ltd.) according to the 1-1/2-1 air pressure method³). The closed cell porosity (%) was calculated according to the following equation and the average of 5 test pieces was regarded as the closed cell porosity (%). The air comparison densitometer was calibrated with standard balls (large: 28.96cc, small: 8.58 cc). The density of the resin was as follows: VYLON GM-913, VYLON GM-915, and PELPRENE P-55B: 1.15g/cm³，PELPRENE GP-400：1.12g/cm³，PELPRENE GP-475：1.17g/cm³，PELPRENE GP-600：1.19g/cm³Polyurethane: 1.20g/cm³And polyethylene terephthalate: 1.39g/cm³。

Closed cell ratio (%) (B- (test piece mass/resin density))/a × 100

< rebound resilience of foam molded article >

The rebound resilience was measured according to JIS K6400-3: 2011. 2 samples cut from the same foam and subjected to state adjustment for 72 hours or more under an environment of a temperature of 23 ± 2 ℃ and a humidity of 50 ± 5% were stacked and mounted to a rebound tester (FR-2, manufactured by Kobunshi Keiki co., ltd.), steel balls (Φ 5/8 inches, 16.3g) were allowed to freely fall from a height (a) of 500mm, the maximum height (b) of the rebounded balls was read, and the rebound ratio (%) was calculated according to the following formula: (b) /(a). times.100. 3 measurements were made on the same test piece and the average value was taken as the rebound resilience.

< C hardness of foam molded article >

The C hardness of a sample 50 × 50 × 20mm thick conditioned for 72 hours or more in an environment with a temperature of 23 ± 2 ℃ and a humidity of 50 ± 5% was measured on a hardness tester (Asker rubber-plastic durometer type C, manufactured by Kobunshi Keiki co., ltd.). The pressing surface was brought into close contact with the test piece so that the stylus was perpendicular to the measurement surface of the test piece, and the scale was immediately read. The samples were measured at 5 points except for the fusion surface of the expanded particles, and the average value was obtained as the C hardness.

< compression set of foam molded article >

The compression set was measured according to JIS K6767:1999 "foamed Plastic-polyethylene-test method". The thickness was measured at 10kPa according to the dimensional measurement A method of JIS K6250: 2006. The foam molded body was cut to 50X thickness 20mm while leaving the outer layer on the plane perpendicular to the thickness direction, and conditioning was performed for 16 hours under a standard atmosphere of class 2 (temperature 23 ℃ C., relative humidity 50%) according to symbol "23/50" of JIS K7100:1999, followed by measurement under the same standard atmosphere. The thickness a (mm) of the test piece was measured to two decimal places. Next, the test piece was compressed on a compression set tester (model FCS-1, manufactured by Kobunshi Keiki co., ltd.) to a state of 25% deformation of the thickness of the test piece, and after being left for 22 hours, the test piece was taken out of the compression set tester, and the thickness b (mm) 30 minutes after the compression was finished was measured to two decimal places. The compression set (%) was calculated according to the following equation. The test pieces were measured 3 times and the average value was regarded as compression set (%).

Compression set (%) - (A-B)/Ax 100

< compressive stress of foam molded article >

The compressive stress was measured according to the method described in JIS K6767:1999 "foamed Plastic-polyethylene-test method". That is, using a tensilon universal tester (UCT-10T, manufactured by ORIENTEC co., ltd.) and universal tester data processing software (UTPS-458X, manufactured by SOFTBRAIN co., ltd.), the test piece size was 50 × 50 × thickness 20mm (the foamed molded body was cut with a bread slicer while leaving the outer layer on a plane perpendicular to the thickness direction) and the compression speed was 10mm/min (the moving speed per minute was as close to 50% of the test piece thickness as possible). A point at the intersection of the linear portion of the compressive modulus and the displacement axis was determined and the compressive stress (kPa) at 25% of the compressive thickness and 50% of the compressive thickness was measured. The 3 test pieces were conditioned under a standard atmosphere of the symbol "23/50" (temperature 23 ℃, relative humidity 50%), class 2 according to JIS K7100:1999 for 16 hours, followed by measurement under the same standard atmosphere.

25% compressive stress sigma₂₅Calculated according to the following equation:

σ₂₅＝10³×F₂₅/A₀

σ₂₅: compressive stress (kPa)

F₂₅: load at 25% deformation (N)

A₀: initial cross-sectional area (mm) of test piece²)

50% compressive stress sigma₅₀Calculated according to the following equation:

σ₅₀＝10³×F₅₀/A₀

σ₅₀: compressive stress (kPa)

F₅₀: load at 50% deformation (N)

A₀: initial cross-sectional area (mm) of test piece²)

< fusion Rate of expanded molded article >

On the surface of the molded foam (400X 300X 20mm in thickness), a cutting line (score) having a depth of about 5mm was made with a cutter knife along a straight line connecting the centers of a pair of long sides, and the molded foam was divided into two parts along the cutting line. For the expanded particles at the fracture surface of the equally divided expanded molded body, an arbitrary region including 100 expanded particles is set, in which the number of expanded particles broken within the expanded particles (a) and the number of expanded particles broken at the interface between the expanded particles (b) are counted, and the fusion rate F (%) is calculated according to the following equation:

F(％)＝a/(a+b)×100

< amount of impregnation gas of Expandable beads (butane gas, carbon dioxide gas) >

The mass W1(g) of the obtained expandable beads was immediately measured and left to stand for 24 hours in an environment at a temperature of 23. + -. 2 ℃ and a humidity of 50. + -. 5%. After standing, the mass W2(g) of the expandable beads was measured, and the amount of impregnating gas was calculated according to the following equation:

the amount of impregnation gas (mass%) of the expandable beads was (W1-W2)/W1 × 100

< amount of impregnation gas (nitrogen gas) of expanded beads >

The mass W1(g) of the expanded beads before the internal pressure was applied was measured. Next, the mass W2(g) of the expanded beads containing nitrogen gas after the internal pressure was applied was measured. The amount of impregnation gas of the expanded beads is calculated according to the following equation:

the amount of impregnation gas (mass%) of the expanded beads was (W2-W1)/W2 × 100

< example 1>

(1) Expandable particles

An autoclave having a stirrer and having an internal volume of 5L was charged with 2kg (100 parts by mass) of ester-based elastomer (trade name: "PELPRENE GP-400", manufactured by Toyobo co., ltd., hard segment: polybutylene terephthalate, soft segment: aliphatic polyether) resin particles, 2.5L of distilled water, 0.13 part by mass of a surfactant (sodium linear alkylbenzene sulfonate, trade name: "Newrex R", manufactured by Yuka Sangyo co., ltd.), and 0.5 part by mass of an organic bubble modifier (ethylene bisstearamide, trade name: "Kao Wax EBFF", manufactured by Kao Corporation), and then the autoclave was sealed, and then 12 parts by mass of a blowing agent butane (isobutane: 7:3) was injected together with nitrogen gas under stirring. The autoclave was then heated at 100 ℃ for 3 hours and then cooled to 25 ℃. After completion of the cooling, the autoclave was depressurized, and the surfactant and the excess cell regulator were immediately washed with distilled water and dehydrated, thereby obtaining expandable particles. The amount of impregnation gas of the expandable beads was 8.5 mass%.

(2) Expanded particles

An agglomeration inhibitor (0.25 parts by mass, polyoxyethylene polyoxypropylene glycol, trade name: "EPAN 450", manufactured by DKS co., ltd.) was applied to 1.5kg (100 parts by mass) of expandable beads, which were then charged into a cylindrical pre-expander having an internal volume of 50L equipped with a stirrer, and heated with steam at a gauge pressure of 0.21MPa while stirring, to obtain expanded beads.

(3) Foamed molded article

The expanded beads were charged into an autoclave, nitrogen gas of gauge pressure 1.2MPa was injected and left standing at 30 ℃ for 18 hours, thereby impregnating the expanded beads with nitrogen gas (internal pressure was applied). The impregnation amount of nitrogen gas was 2.6 mass%.

The expanded beads were taken out of the autoclave, immediately filled into a molding cavity having steam holes of 400mm × 300mm × 20mm in thickness and subjected to thermoforming with steam at a surface pressure of 0.27MPa, to thereby obtain a foamed molded article.

A cross-sectional image of the obtained foamed molded body is shown in fig. 1.

< example 2>

(1) Expandable particles

Expandable particles were produced in the same manner as in example 1, except that the base resin was changed to an ester-based elastomer (trade name: "PELPRENE GP-475", manufactured by Toyobo co., ltd., hard segment: polybutylene terephthalate and polybutylene isophthalate, soft segment: aliphatic polyether). The amount of impregnation gas of the expandable beads was 4.8 mass%.

(2) Expanded particles

Expanded particles were produced in the same manner as in example 1, except that heating was performed with water vapor having a surface pressure of 0.20 MPa.

(3) Foamed molded article

A foam-molded body was produced in the same manner as in example 1, except that thermoforming was performed with water vapor having a surface pressure of 0.18 MPa. The nitrogen impregnation amount of the expanded beads was 3.5 mass%.

A cross-sectional image of the obtained foamed molded body is shown in fig. 2.

< example 3>

(1) Expandable particles

Expandable particles were produced in the same manner as in example 1, except that the base resin was changed to an ester-based elastomer (trade name: "VYLON GM-913", manufactured by Toyobo co., ltd., hard segment: polybutylene terephthalate and polybutylene isophthalate, soft segment: aliphatic polyether). The amount of impregnation gas of the expandable beads was 8.8 mass%.

(2) Expanded particles

Expanded particles were produced in the same manner as in example 1, except that heating was performed with water vapor having a surface pressure of 0.06 MPa.

(3) Foamed molded article

A foam-molded body was produced in the same manner as in example 1, except that thermoforming was performed with water vapor having a surface pressure of 0.06 MPa. The nitrogen impregnation amount of the expanded beads was 1.7 mass%.

A cross-sectional image of the obtained foamed molded body is shown in fig. 3.

< example 4>

(1) Expandable particles

Expandable particles were produced in the same manner as in example 1, except that the base resin was changed to an ester-based elastomer (trade name: "VYLON GM-915", manufactured by Toyobo co., ltd., hard segment: polybutylene terephthalate and polybutylene isophthalate, soft segment: aliphatic polyether). The amount of impregnation gas of the expandable beads was 6.1 mass%.

(2) Expanded particles

(3) Foamed molded article

An expanded molded body was produced in the same manner as in example 1, except that the thermoforming was performed with water vapor having a gauge pressure of 0.1 MPa. The nitrogen impregnation amount of the expanded beads was 1.0 mass%.

A cross-sectional image of the obtained foamed molded body is shown in fig. 4.

< example 5>

(1) Expandable particles

Expandable particles were produced in the same manner as in example 1, except that the base resin was changed to an ester-based elastomer (trade name: "PELPRENE P-55B", manufactured by Toyobo co., ltd., hard segment: polybutylene terephthalate, soft segment: aliphatic polyether). The amount of impregnation gas of the expandable beads was 7.8 mass%.

(2) Expanded particles

Expanded particles were produced in the same manner as in example 1, except that heating was performed with water vapor having a surface pressure of 0.35 MPa.

(3) Foamed molded article

An expanded molded body was produced in the same manner as in example 1, except that the thermoforming was performed with water vapor having a gauge pressure of 0.4 MPa. The nitrogen impregnation amount of the expanded beads was 1.0 mass%.

A cross-sectional image of the obtained foamed molded body is shown in fig. 5.

< example 6>

(1) Expandable particles

Expandable particles were produced in the same manner as in example 1, except that the base resin was changed to an ester-based elastomer (trade name: "PELPRENE GP-600", manufactured by Toyobo co., ltd., hard segment: polybutylene terephthalate and polybutylene isophthalate, soft segment: aliphatic polyether). The amount of impregnation gas of the expandable beads was 5.5 mass%.

(2) Expanded particles

Expanded particles were produced in the same manner as in example 1, except that heating was performed with water vapor at a surface pressure of 0.28 MPa.

(3) Foamed molded article

A foam-molded body was produced in the same manner as in example 1, except that thermoforming was performed with water vapor having a surface pressure of 0.40 MPa. The nitrogen impregnation amount of the expanded beads was 1.3 mass%.

A cross-sectional image of the obtained foamed molded body is shown in fig. 6.

< example 7>

(1) Expandable particles

2kg of ester-based elastomer (trade name: "PELPRENE GP-475", manufactured by Toyobo co., ltd., hard segment: polybutylene terephthalate and polybutylene isophthalate, soft segment: aliphatic polyether) resin particles were charged into an autoclave having an internal volume of 5L, and the autoclave was sealed, followed by pressurization with carbon dioxide (blowing agent) from atmospheric pressure to a gauge pressure of 4 MPa. The autoclave was then allowed to stand at 23 ℃ for 24 hours, and then decompressed to obtain expandable particles. The amount of impregnation gas of the expandable beads was 7.0 mass%.

(2) Expanded particles

Expanded particles were produced in the same manner as in example 1, except that heating was performed with water vapor at a surface pressure of 0.11 MPa.

(3) Foamed molded article

A foam-molded body was produced in the same manner as in example 1, except that thermoforming was performed with water vapor having a surface pressure of 0.21 MPa. The nitrogen impregnation amount of the expanded beads was 0.3 mass%.

A cross-sectional image of the obtained foamed molded body is shown in fig. 7.

< example 8>

(1) Resin particle

An ester-based elastomer (100 parts by mass, trade name: "PELPRENE GP-475", manufactured by Toyobo co., ltd., hard segment: polybutylene terephthalate and polybutylene isophthalate, soft segment: aliphatic polyether) and 0.3 part by mass of an organic-based bubble controlling agent (ethylene bisstearamide, trade name: "Kao Wax EBFF", manufactured by Kao Corporation) were supplied to a single-screw extruder and melt-kneaded at 180 to 280 ℃. The ester-based elastomer in a molten state is then cooled to adjust viscosity and extruded through each nozzle of a multi-nozzle metal die (having 8 nozzles with a diameter of 1.3 mm) mounted on the tip of a single-screw extruder, and then cut in water at 30 to 50 ℃. The obtained resin particles have a particle length L of 1.4 to 1.8mm and an average particle diameter D of 1.4 to 1.8 mm.

(2) Expandable particles

To an autoclave equipped with a stirrer having an internal volume of 5L, 1.5kg (100 parts by mass) of resin particles, 3L of distilled water, and 4g of a surfactant (sodium linear alkylbenzene sulfonate, trade name: "Newrex R", manufactured by Yuka Sangyo co., ltd.) were charged, and the autoclave was sealed, followed by injecting 16 parts by mass of a blowing agent butane (n-butane: isobutane: 7:3) under stirring. The autoclave was then heated at 100 ℃ for 2 hours and then cooled to 25 ℃. After completion of cooling, the autoclave was depressurized, the surfactant was washed with distilled water and dehydrated, thereby obtaining expandable particles. The amount of impregnation gas of the expandable beads was 7.9 mass%.

(3) Expanded particles

An agglomeration inhibitor (0.25 parts by mass, polyoxyethylene polyoxypropylene glycol, trade name: "EPAN 450", manufactured by DKS co., ltd.) was applied to 1.5kg (100 parts by mass) of expandable beads, which were then charged into a cylindrical pre-expander having an internal volume of 50L equipped with a stirrer, and heated with steam at a gauge pressure of 0.11MPa while stirring, to obtain expanded beads.

(4) Foamed molded article

The expanded beads were charged into an autoclave, nitrogen gas of gauge pressure 0.5MPa was injected and left standing at 30 ℃ for 18 hours to impregnate the expanded beads with nitrogen gas (internal pressure was applied). The amount of nitrogen gas impregnated was 1.1 mass%.

The foamed pellets were taken out of the autoclave, immediately filled into a molding cavity having a water vapor pore size of 400mm × 300mm × 20mm in thickness and subjected to thermoforming with water vapor at a surface pressure of 0.21MPa, thereby obtaining a foam.

A cross-sectional image of the obtained foamed molded body is shown in fig. 8.

< example 9>

(1) Resin particle

Resin particles were prepared in the same manner as in example 8, except that the base resin was changed to an ester-based elastomer (trade name: "PELPRENE GP-600", manufactured by Toyobo co., ltd., hard segment: polybutylene terephthalate and polybutylene isophthalate, soft segment: aliphatic polyether). The obtained resin particles have a particle length L of 1.4 to 1.8mm and an average particle diameter D of 1.4 to 1.8 mm.

(2) Expandable particles

Expandable particles were produced in the same manner as in example 8. The amount of impregnation gas of the expandable beads was 7.6 mass%.

(3) Expanded particles

Expanded particles were produced in the same manner as in example 8, except that heating was performed with water vapor having a surface pressure of 0.26 MPa.

(4) Foamed molded article

A foam-molded body was produced in the same manner as in example 8, except that thermoforming was performed with water vapor having a surface pressure of 0.40 MPa. The nitrogen impregnation amount of the expanded beads was 1.6 mass%.

A cross-sectional image of the obtained foamed molded body is shown in fig. 9.

< example 10>

(1) Resin particle

Resin pellets were produced in the same manner as in example 8, except that the diameter of the multi-nozzle metal die of the extruder was changed from 1.3mm to 1.0 mm. The obtained resin particles have a particle length L of 1.1 to 1.5mm and an average particle diameter D of 1.1 to 1.5 mm.

(2) Expandable particles

To a heatable and sealable pressure-resistant rotary mixer having an internal volume of 43L, 15kg (100 parts by mass) of resin particles, 0.25 part by mass of a coalescence inhibitor (polyoxyethylene polyoxypropylene glycol, trade name: "EPAN 450", manufactured by DKS co., ltd.), and 0.3 part by mass of distilled water were charged, and the mixer was sealed, and 16 parts by mass of a blowing agent butane (n-butane: isobutane: 7:3) was injected into the mixer in a rotating state. Then, the mixer was heated at 85 ℃ for 2 hours in a rotating state, cooled to 25 ℃ and decompressed, thereby obtaining expandable particles. The amount of impregnation gas of the expandable beads was 5.9 mass%.

(3) Expanded particles

1.5kg of expandable beads were charged into a cylindrical pre-expander having an internal volume of 50L and equipped with a stirrer, and heated with steam at a gauge pressure of 0.12MPa while stirring, thereby obtaining expanded beads.

(4) Foamed molded article

The expanded beads were charged into an autoclave, nitrogen gas of 0.5MPa gauge pressure was injected and left to stand at 30 ℃ for 18 hours, thereby impregnating the expanded beads with nitrogen gas (internal pressure was applied). The amount of nitrogen gas impregnated was 0.7 mass%.

The foamed pellets were taken out of the autoclave, immediately filled into a molding cavity having steam holes of 400mm × 300mm × 20mm in thickness, and subjected to thermoforming with steam of 0.22MPa in surface pressure, thereby obtaining a foam.

Fig. 10 shows a sectional image of the obtained molded foam.

< example 11>

(1) Resin particle

Resin particles were prepared in the same manner as in example 10. The obtained resin particles have a particle length L of 1.1 to 1.5mm and an average particle diameter D of 1.1 to 1.5 mm.

(2) Expandable particles

Expandable particles were produced in the same manner as in example 10. The amount of impregnation gas of the expandable beads was 5.8 mass%.

(3) Expanded particles

Expanded particles were produced in the same manner as in example 10, except that heating was performed with water vapor having a surface pressure of 0.13 MPa.

(4) Foamed molded article

A foam-molded body was produced in the same manner as in example 10, except that thermoforming was performed with water vapor having a surface pressure of 0.21 MPa. The nitrogen impregnation amount of the expanded beads was 1.0 mass%.

A cross-sectional image of the obtained foamed molded body is shown in fig. 11.

< comparative example 1>

A polyurethane foam molded body in the midsole of a sports shoe (trade name: "Energy Boost", manufactured by Adidas) was cut out and subjected to various evaluations.

Fig. 12 shows a sectional image of the cut molded foam.

< comparative example 2>

(1) Expanded particles

A polyethylene terephthalate composition comprising 100 parts by mass of polyethylene terephthalate (trade name: "SA-135", manufactured by Mitsui Chemicals, Inc.), 1.8 parts by mass of a master batch containing polyethylene terephthalate and talc (polyethylene terephthalate content: 60% by mass, talc content: 40% by mass, intrinsic viscosity of polyethylene terephthalate: 0.88), and 0.20 part by mass of pyromellitic anhydride was supplied to a uniaxial extruder having a bore diameter of 65mm and an L/D ratio of 35 and melt-kneaded at 290 ℃.

Thereafter, butane composed of 30 mass% of isobutane and 70 mass% of n-butane was injected from the middle of the extruder into the polyethylene terephthalate composition in a molten state at 0.7 mass part with respect to 100 mass parts of the polyethylene terephthalate, thereby uniformly dispersing the butane in the polyethylene terephthalate. Thereafter, the polyethylene terephthalate composition in a molten state was cooled to 280 ℃ at the front end portion of the extruder, and then the polyethylene terephthalate composition was extrusion-foamed through each nozzle of a multi-nozzle metal die mounted on the front end of the extruder. The extrusion amount of the polyethylene terephthalate composition was 30 kg/h.

The multi-nozzle metal mold has 20 nozzles each having an outlet portion with a diameter of 1mm, and all the nozzle outlet portions are provided at equal intervals on a virtual circle assumed to have a diameter of 139.5mm on the front end surface of the multi-nozzle metal mold. On the outer peripheral surface of the rear end portion of the rotary shaft, 2 rotary blades were integrally provided with a phase difference of 180 ° in the circumferential direction of the rotary shaft, and each rotary blade was formed so as to move on a virtual circle while always being in contact with the front end surface of the multi-nozzle metal mold. Further, the cooling member includes a cooling drum having a front circular front portion and a cylindrical peripheral wall portion having an inner diameter of 320mm extending rearward from an outer peripheral edge of the front portion. Cooling water of 20 c was supplied to the cooling drum through a supply pipe and a supply port of the cooling drum. The volume in the cooling drum was 17684cm³. By means ofThe cooling water spirally advances along the inner circumferential surface of the peripheral wall portion of the cooling drum by a centrifugal force generated by a flow velocity generated when the cooling water is supplied from the supply pipe to the inner circumferential surface of the peripheral wall portion of the cooling drum. The cooling liquid gradually spreads in a direction perpendicular to the traveling direction while traveling along the inner peripheral surface of the peripheral wall portion, and as a result, the inner peripheral surface of the peripheral wall portion in front of the supply port of the cooling drum is completely covered with the cooling liquid.

The polyethylene terephthalate extrudate extruded and foamed through the outlet portion of each nozzle of the multi-nozzle metal mold was cut with a rotary blade while rotating the rotary blade arranged on the front end face of the multi-nozzle metal mold at a rotation speed of 2500rpm, thereby producing a pellet-shaped cut matter in an approximately spherical shape. The polyethylene terephthalate extrudate includes an unfoamed portion immediately after being extruded from a nozzle of a multi-nozzle metal die and a foaming portion being foamed continuous with the unfoamed portion. The polyethylene terephthalate extrudate was cut at the open end of the outlet portion of the nozzle and cut at the unfoamed portion.

For the production of polyethylene terephthalate foamed particles for foam molding in a mold, a multi-nozzle metal mold was used in advance without a rotating shaft, and a cooling member was made to avoid the multi-nozzle metal mold. By extrusion foaming a polyethylene terephthalate extrudate from such an extruder, it was observed that the polyethylene terephthalate extrudate includes an unfoamed portion that has just been extruded from the nozzle of a multi-nozzle metal die and a foaming portion that is being foamed that is continuous with the unfoamed portion.

Next, a rotating shaft was mounted to a multi-nozzle metal mold and a cooling member was disposed at a predetermined position, and then the rotating shaft was rotated, and the polyethylene terephthalate extrudate was cut with a rotating blade at the opening end of the outlet portion of the nozzle, thereby producing a granulated cut product. The granular cut matter is blown outward or forward by the cutting stress of the rotary blade, collides with the cooling water flowing along the inner surface of the cooling drum of the cooling part from the direction of an oblique angle with respect to the surface of the cooling water, follows the cooling water from the upstream side to the downstream side of the flow of the cooling water, enters the cooling water, and is immediately cooled, thereby producing foamed particles. The obtained expanded particles were discharged together with cooling water through the discharge port of the cooling drum and then separated from the cooling water in the dehydrator.

(2) Foamed molded article

A molding cavity having a water vapor hole size of 400mm X300 mm X20 mm in thickness was filled with expanded beads, and the expanded molded article was obtained by heating and molding with water vapor at a surface pressure of 0.13 MPa.

A cross-sectional image of the obtained foamed molded body is shown in fig. 13.

The hard segment amount, terephthalic acid component amount, isophthalic acid component amount, melting point, crystallization temperature, crystallization heat and resin shore D hardness of the resin particles of examples 1 to 11 and comparative examples 1 to 2, the bulk density of the expanded particles, and the density, average particle diameter, average cell diameter (surface layer portion), average cell diameter (central portion), closed cell porosity, spring back ratio, C hardness, compression set, 25% compressive stress, 50% compressive stress and fusion ratio of the expanded molded article are summarized in table 1.

From Table 1, it is found that the foam molded articles of examples 1 to 11 exhibit high resilience and low density.

< measurement example >

The hard segment amount of the ester-based elastomer of examples 1 to 6, and the amount of the terephthalic acid component and the amount of the isophthalic acid component in the elastomer were measured by the following methods. The ester-based elastomers used in examples 2, 7, 8, 10, and 11 and the ester-based elastomers used in examples 6 and 9 were each the same.

40mg of the ester elastomer was dissolved in 2g of 1,1,1,3,3, 3-hexafluoro-2-propanol (HFIP-d) containing Tetramethylsilane (TMS) as an internal standard substance₂Deuterated solvents). In that¹H-NMR, measurement of the resulting solution on type AL400 manufactured by JEOL Ltd, to obtain ester-based elastomers¹H-NMR spectrum. Method for producing ester-based elastomer of examples 1 to 6¹H-NThe MR spectra are shown in FIGS. 14-19.

The obtained spectra were compared with those of known substances, and it was found that the ester-based elastomers of examples 2 to 4 and 6 were formed of a terephthalic acid component, an isophthalic acid component and a butanediol component.

From the obtained spectra, the area ratio of peaks corresponding to the hydrogens (a) to (i) (see the following chemical formulae) of the respective components was calculated (the reference was determined as 4.0000 while assuming that the area of the hydrogen corresponding to the terephthalic acid component corresponds to 4 hydrogen atoms). The calculated area ratios are shown in table 2.

[ formula 1]

[ Table 2]

From the area ratios shown in table 2, the molar ratios and mass ratios of the respective components were calculated according to the following equations. The butanediol component is calculated as a monobutanediol component and a polytetramethylene glycol component. The calculation results are shown in table 3.

(1) Molar ratio of

Terephthalic acid component: 100 × (f/4)/[ (f/4) + (i/1) + (c/4) + (b/8) ]

Isophthalic acid component: 100 × (i/1)/[ (f/4) + (i/1) + (c/4) + (b/8) ]

Monobutylene glycol component: 100 × (c/4)/[ (f/4) + (i/1) + (c/4) + (b/8) ]

A polybutylene glycol component: 100 × (b/8)/[ (f/4) + (i/1) + (c/4) + (b/8) ]

(2) Mass ratio of

Terephthalic acid component: 100X 148X (f/4)/{ 148X (f/4) + 148X (i/1) + 72X (c/4) + 72X [ d + (b/2) ]/4}

Isophthalic acid component: 100X 148X (i/1)/{ 148X (f/4) + 148X (i/1) + 72X (c/4) + 72X [ d + (b/2) ]/4}

Monobutylene glycol component: 100X 72 (c/4)/{148 (f/4) +148 (i/1) +72 (c/4) +72 (d + (b/2))/4 }

A polybutylene glycol component: 100X 72X [ d + (b/2) ]/4/{ 148X (f/4) + 148X (i/1) + 72X (c/4) + 72X [ d + (b/2) ]/4} in the formula

[ Table 3]

From the area ratios shown in table 2, the composition ratio (% by mass) of the hard segment and the soft segment in each elastomer was calculated according to the following equation. The calculation results are shown in table 1. It is defined that the hard segment is formed of a polybutylene terephthalate component, a polybutylene isophthalate component, a terephthalic acid component and an isophthalic acid component and the soft segment is formed of a polybutylene glycol component.

(1) Hard segment

100×{148×(f/4)+148×(i/1)+72×(c/4)}/{148×(f/4)+148×(i/1)+72×(c/4)+72×[d+(b/2)]/4}

(2) Soft segment

100×{72×[d+(b/2)]/4}/{148×(f/4)+148×(i/1)+72×(c/4)+72×[d+(b/2)]/4}

Claims

1. An ester-based elastomer foam molded body comprising a fusion body of foamed particles containing an ester-based elastomer as a base resin, wherein the ester-based elastomer comprises a hard segment and a soft segment, the hard segment is formed from a dicarboxylic acid component and a diol component, and the soft segment is an aliphatic polyether and/or polyester, the dicarboxylic acid component comprises a terephthalic acid component and an isophthalic acid component and contains the isophthalic acid component in a proportion of 5 to 30 mass%.

2. The molded ester elastomer foam according to claim 1, wherein the heat of crystallization of the ester elastomer is 0 to 30 mJ/mg.

3. The molded ester elastomer foam according to claim 1, wherein the ester elastomer contains the hard segment in a proportion of 30 to 80% by mass.

4. The ester elastomer foam molding according to claim 1, wherein the average cell diameter of the foamed particles in the fusion body at the center is 10 to 200 μm and the average cell diameter of the surface layer is 50 to 300 μm.

5. The molded ester elastomer foam according to claim 1, wherein the molded ester elastomer foam has an apparent density of 0.02 to 0.4g/cm³And the rebound resilience is 50-100%.

6. The molded ester-based elastomer foam according to claim 1, which is used for any one of an insole, a midsole and an outsole.

7. A midsole comprising the foamed molding according to claim 6.

8. A sole comprising the midsole of claim 7.

9. An ester-based elastomer foamed particle comprising an ester-based elastomer as a base resin and capable of providing a foamed molded body comprising a fusion body of foamed particles, wherein the ester-based elastomer comprises a hard segment and a soft segment, the hard segment is formed of a dicarboxylic acid component and a diol component, and the soft segment is an aliphatic polyether and/or polyester, the dicarboxylic acid component comprises a terephthalic acid component and an isophthalic acid component and contains the isophthalic acid component in a proportion of 5 to 30 mass%.

10. The ester-based elastomer foamed particles according to claim 9, which satisfy any of the following requirements (i) to (iv):

(i) the ester elastomer has a heat of crystallization of 0 to 30 mJ/mg;

(ii) the ester-based elastomer contains the hard segment in a proportion of 30 to 80 mass%;

(iii) the ester elastomer foamed particles can provide a foamed molded body in which the average cell diameter of the center portion of the foamed particles in the fused body is 10 to 200 [ mu ] m and the average cell diameter of the surface layer portion is 50 to 300 [ mu ] m; and

(iv) the ester-based elastomer foamed particles can provide a display density of 0.02-0.4 g/cm³And a resilience of 50 to 100%.